| Innervation of extrafusal and intrafusal fibres in snake muscle. | |
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MedLine Citation:
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PMID: 4271352 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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1. Intrafusal fibres of snake receive motor supply from branches of axons innervating extrafusal motor units. By intramuscular stimulation of motor units by single shocks, and critical curarization of the muscle, we have identified at least some of the motor units contributing motor supply to individual intrafusal fibres. Intrafusal fibre activation was observed by visual examination of the contracting intrafusal fibre, and by recording the resulting spindle afferent discharge.2. The main finding is that in some cases the motor supply to one intrafusal fibre comes from more than one motor unit. The contributing motor units may be either dissimilar twitch units, or twitch and tonic units. Thus some of the intrafusal fibres studied showed polyneuronal motor innervation of heterogeneous origin.3. In critically curarized muscle, the time course of a spindle afferent discharge, following single-shock stimulation of a motor unit contributing motor supply to the intrafusal fibre, showed little variation with the type of motor unit being stimulated.4. The response of each spindle to a standard stretch was recorded. There was no correlation between dynamic index and type of motor unit or units contributing motor supply. However, the method limits the value of negative findings, and this is discussed.5. The contraction times and tensions of a sample of motor unit isometric twitches are described. |
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Authors:
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G S Cliff; R M Ridge |
Publication Detail:
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Type: In Vitro; Journal Article |
Journal Detail:
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Title: The Journal of physiology Volume: 233 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1973 Aug |
Date Detail:
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Created Date: 1974-01-31 Completed Date: 1974-01-31 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 1-18 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Action Potentials Animals Anura Cats Electric Stimulation Motor Neurons / physiology Muscle Contraction Muscle Spindles / drug effects, physiology* Muscles / innervation Myofibrils / physiology* Neurons / physiology Neurons, Afferent / physiology Snakes / physiology* Tubocurarine / pharmacology |
| Chemical | |
Reg. No./Substance:
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57-95-4/Tubocurarine |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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